A plurality of devices are used in the area of medical diagnostics fully automatically carrying out the necessary method steps, such as, for example, pipetting, mixing, incubating, centrifuging, measuring etc. The samples that are analyzed by means of such devices are, in the majority of cases, human or animal body fluids or other analyte-containing fluids to which frequently at least one test reagent has to be added. The storage, the removal, the transfer and the addition of fluids, which can be located in the most varied containers, are, therefore, essential operations in the interior of the diagnostic devices.
One criterion to be taken into consideration when setting up tests on partly automatic or fully automatic diagnostic devices is the storage life of the reagents when stored in the device, the so-called on-board stability, which is influenced definitively by the conditions in the device. Particularly problematic are the loss in mass of fluid reagents brought about by evaporation and the risk of contamination. To determine analytes in a standardized and reliable manner, it is essential to use reagents in a defined composition, which means that any changes in concentration, brought about by fluid losses, can impair the quality or the so-called performance of the entire test. The reason why fluid reagents evaporate is that they have to be directly accessible to the automatic pipettors and are, consequently, not as a rule hermetically sealed.
Depending on the design of the devices or pipettors, as is known, different measures are taken to reduce the evaporation of fluids from the reagent containers. For example, many diagnostic devices have cooled holders or positions into which the reagent containers are inserted. By cooling the reagents, the evaporative fluid loss can be reduced in a considerable manner. Another measure for reducing the effects of evaporation is decreasing the cross-sectional opening of the reagent container, which, however, is only able to be adapted to a restricted extent, limited by the dimensions of the pipettor. The use of closure caps or plugs that are more or less hermetically sealed is also customary.
A particularly impermeable protection against evaporation and a particularly efficient protection against contamination is offered by closure devices which seal off the opening of the reagent container as hermetically as possible, such as, for example, screw-type closures or snap-type closures, and which are designed such that they can be automatically opened and closed again by means of a corresponding mechanism in the diagnostic device. However, one disadvantage is that extremely complicated mechanisms and devices have to be installed on the devices for automatically opening and closing such closure devices.
Another closure device which ensures efficient protection against evaporation and contamination is described in EP-A2-1046915. This latter describes a two-part reagent container closure comprising a closure body with an opening which is mounted on the opening of the reagent container. A closure cover, which releases the opening of the reagent container in the open position and closes the opening of the reagent container in the closed position, is movably connectable to the closure body. The opening and closing of the opening of the reagent container is effected by the closure cover being moved in a horizontal plane in relation to the closure body. So that the closure device can be actuated automatically, the closure cover has a so-called entrainment means and the ram of a corresponding arrangement of the device, in which the reagent container is located, is able to cooperate with said entrainment means. The horizontal movement of the closure cover is brought about by a horizontal movement of the ram or of the reagent container and the reagent container is consequently opened or closed.
An additional challenge is connected to the storage of light-sensitive reagents in diagnostic devices. Modern test methods are increasingly based on highly sensitive photochemical methods. The reagents used in this case contain light-sensitive components, such as photo-sensitizers or chemiluminescent or fluorescent substances which are excited by the effect of light. In order to ensure the on-board stability of light-sensitive reagents, any effect of light must be avoided as much as possible. To this end, these types of reagents are usually filled in containers which are produced from a light-tight material, preferably a colored plastics material. The reagent containers are hermetically sealed for the transporting and storing of the reagents until they are positioned in the diagnostic device. The reagent container opening is usually heat-sealed with a light-tight foil by the manufacturer for this purpose.
One disadvantage with these types of foil seals, which are also used, moreover, for the transporting and storing of non-light-sensitive reagents, is that the foil has to be removed by hand from the reagent container by the user before a suitable automatically re-closable closure device can be applied, by means of which the reagent container is then positioned in the diagnostic device. The manual removal of the foil and the resultant handling at the opened reagent container involves the risk of the reagent being shaken or contaminants passing into the container. As the user must, therefore, act particularly carefully in order to avoid the named risks, the removal of foil seals and the ensuing mounting of the closure devices is also an operating step that is expensive in time and consequently cost. One particular disadvantage when removing the foil from reagent containers that contain light-sensitive reagents and then mounting the closure device is that these steps should be carried out, as much as possible, protected from light, i.e. in a dark room. The user's blind handling, however, increases the named risks of shaking and contaminating the container.